Various tactile sensors that simulate a human feeling in an engineering manner have been developed. Especially, a tactile sensor that is made by semiconductor micromachining techniques and can read a lot of sensor signals with less wiring allows a lot of sensor parts to be arranged in high density, and advantageously has high positional resolution.
As the tactile sensors made by semiconductor micromachining techniques, for example, a tactile sensor that utilizes deformation of a thin silicon diaphragm (Patent Literature 1) and a tactile sensor that utilizes deformation of hinge structure (Patent Literature 2) are known. Each of these conventional tactile sensors disclosed in Patent Literature 1 and Patent Literature 2 uses the surface of a substrate as a sensing surface, and is configured to make the surface of the substrate come in contact with a measuring object to read the deformation by the force applied in a vertical direction to the substrate. Therefore, such sensing structure is configured in a thickness direction of the substrate.
However, such a tactile sensor with the surface of the substrate used as a sensing surface allows little displacement due to the limitation of material properties and/or thickness of the substrate. Further, the flexibility in designing a tip shape of a contact of a tactile sensor is limited because the contact is vertically arranged to the substrate, and thus the tip shape appropriate to various measuring objects cannot be designed. Therefore, the problem is that such a tactile sensor is poor in detection performance with regard to fine ruggedness on the surface of a measuring object, and thus has difficulty in evaluating a fine touch feeling.
Moreover, stable detection of tactile sense and/or feeling requires that a tactile sensor performs sensing while keeping applying force (contact surface pressure) constant to a measuring object. However, it is difficult for conventional tactile sensors to keep such a measuring condition.